Birds are providing some insight into contamination in the Great Lakes.

Scientists with the U.S. Geological Survey are observing the nesting patterns of tree swallows
along the banks of the lakes and are collecting blood from their babies to monitor levels of some
toxins including mercury, chromium and cadmium.

If these metals and chemicals are in birds, they likely are in humans as well, researchers
say.

The program started in 2010 with 20 testing sites as part of the Great Lakes Restoration
Initiative, which aims to clean up the lakes and surrounding areas.

Teams work sites for two years before choosing new ones. Five sites have been in Ohio, including
on the Maumee and Ottawa rivers on the Ohio-Michigan border. A site on the Cuyahoga River will be
added this year.

Testing occurs mostly in May and June, before the birds fly south for the winter months.

The process starts by identifying areas where tree swallows go. Then researchers put up boxes
where the birds nest and lay eggs. Researchers check the nest boxes weekly, said Christine Custer,
a wildlife biologist and one of the lead scientists on the project.

“We check to see how many eggs are laid, how many hatch, how many grow up and fly away,” she
said.

They take eggs that don’t hatch as well as blood samples from the baby birds. Both can show
signs of contaminants.

“A lot of these contaminants are associated with the lipids in the birds, so what’s in the egg
relates to what the (mother has) been exposed to,” Custer said.

So far, the data show that heavy metals, such as mercury, chromium and cadmium, are the biggest
problems at the Ohio sites. Coal-fired power plants and metal-processing facilities are the likely
sources.

In 2013, a U.S. Environmental Protection Agency analysis found that power plants produce at
least half of the industrial toxins in waterways nationwide.

The EPA estimates that power plants release 5.5 billion pounds of pollutants into streams,
rivers and lakes each year. Among them are nearly 1.8 billion pounds of dissolved metals, including
mercury, lead, cadmium and selenium, which is a metal linked to kidney, liver and nervous-system
damage in humans.

The main goal of the U.S. Geological Survey program is to provide information to the states
about the health of their lakes.

The Ohio EPA uses more than a dozen benchmarks, called “beneficial-use impairments,” to evaluate
the health of the lakes. Among those are bird and animal deformities, reproductive problems and
degraded fish and wildlife populations.

“Our piece is important because the states need more information about each of these 14
(benchmarks),” Custer said. “We’re well positioned, given our history of work on contaminants in
birds, to provide this information to the state.”

The testing process looks for about nine toxins, including organic compounds such as PCBs as
well as the heavy metals.

In humans, exposure to cadmium is linked to osteoporosis, chronic obstructive lung disease and
several kinds of cancers, according to the World Health Organization. Mercury exposure can cause
neurological problems and affect the brain, heart, kidneys, lungs and immune system.

The problem with PCBs is that they don’t break down easily, said Sara DeLeon, a researcher at
Drexel University in Philadelphia. She studied the effects of PCBs on birds while earning a
doctorate from Cornell University.

“Wherever (PCBs) are, they weren’t there before,” she said. “They stay in organisms, in the
ecosystem.”

The chemicals can change the way birds sing and act. They also can cause cancer and reproductive
failure.

In humans, PCBs can cause developmental problems in children, who can absorb them through breast
milk. According to the U.S. EPA, PCBs are probable human carcinogens.

“Finding (pollutants) in birds does cause concern for humans and other organisms in the
environment,” DeLeon said.